A biocompatible microemulsion system comprising of isopropyl myristate (IPM) as oil, tween 80 as a non-ionic surfactant and isobuthanol as co-surfactant was studied experimentally at 298.15 K. The pseudo-ternary phase diagram for the microemulsion system has been delineated at different surfactant to co-surfactant mass ratio of 1:1, 2.4:1 and 4:1. Some physico-chemical properties such as density, viscosity, refractive index, conductivity and pH, for a typical surfactant to co-surfactant mass ratio of 2.4:1 were determined precisely. It is verified that the transition point of viscosity, conductivity, refractive index and density occurs at about 30 wt% of water. The transition point could be attributed to either the change in the shape of droplets or the transition from o/w microemulsion phase to bicontinuous phase.